Advanced Subsidiary Unit 1: The Core Principles of Chemistry

Transcript

1 Write your name here Surname Other names Edexcel GCE Centre Number Chemistry Advanced Subsidiary Unit 1: The Core Principles of Chemistry Candidate Number Wednesday 3 June 2009 Morning Time: 1 hour 15 minutes Candidates may use a calculator. Paper Reference 6CH01/01 Total Marks H34471A 2009 Edexcel Limited. 7/7/3/ Instructions Use black ink or ball-point pen. Fill in the boxes at the top of this page with your name, centre number and candidate number. Answer all questions. Answer the questions in the spaces provided there may be more space than you need. Information The total mark for this paper is 80. The marks for each question are shown in brackets use this as a guide as to how much time to spend on each question. Questions labelled with an asterisk (*) are ones where the quality of your written communication will be assessed you should take particular care with your spelling, punctuation and grammar, as well as the clarity of expression, on these questions. A Periodic Table is printed on the back cover of this paper. Advice Read each question carefully before you start to answer it. Keep an eye on the time. Try to answer every question. Check your answers if you have time at the end. *H34471A0128* Turn over

2 SECTION A Answer ALL the questions in this section. You should aim to spend no more than 20 minutes on this section. For each question, select one answer from A to D and put a cross in the box. If you change your mind, put a line through the box and then mark your new answer with a cross. 1 The nucleus of a 23 Na atom contains 11 A 11 protons and 12 neutrons. B C D 11 protons and 12 electrons. 23 protons and 11 neutrons. 23 protons and 11 electrons. (Total for Question 1 = 1 mark) 2 The mass spectrum for a sample of a metal is shown below. relative abundance mass/charge ratio 65 The relative atomic mass of the metal is A 63.2 B 63.4 C 63.6 D 64.0 (Total for Question 2 = 1 mark) 2 *H34471A0228*

3 3 Some mean bond enthalpy values are given in the table below. Bond Mean bond enthalpy / kj mol 1 H H +436 I I +151 H I +299 What is the enthalpy change for the reaction shown below in kj mol 1? H 2 (g) + I 2 (g) 2HI(g) A = +288 B = 288 C (2 299) = 11 D (2 299) = +11 (Total for Question 3 = 1 mark) 4 A compound was analysed and found to contain 1.45 g carbon g hydrogen 1.69 g nitrogen [Relative atomic masses: C = 12; H = 1; N = 14] The empirical formula of the compound is A CH 3 N B CH 4 N C CH 5 N D C 2 H 4 N (Total for Question 4 = 1 mark) *H34471A0328* 3 Turn over

4 g of aluminium sulfate, Al 2 (SO 4 ) 3, was dissolved in water. Calculate the number of sulfate ions, SO 4 2, present in the solution formed. [Assume the molar mass of Al 2 (SO 4 ) 3 is 342 g mol 1 and the Avogadro Constant is mol 1.] A B C D (Total for Question 5 = 1 mark) 6 Calculate the mass of calcium hydroxide, Ca(OH) 2, present in 100 cm 3 of a mol dm 3 solution. [Assume the molar mass of Ca(OH) 2 is 74.0 g mol 1.] A B C D g g 1.85 g 3.70 g (Total for Question 6 = 1 mark) Use this space for any rough working. Anything you write in this space will gain no credit. 4 *H34471A0428*

5 7 The first five successive ionization energies of an element, X, are shown in the table below. Ionization energy first second third fourth fifth Value / kj mol Which ion is X most likely to form when it reacts with chlorine? A X + B X 2+ C X 3+ D X 4+ (Total for Question 7 = 1 mark) 8 Which of the following alkenes exhibits E-Z isomerism? A H 3 CCH=C(CH 3 ) 2 B (CH 3 ) 2 C=CH 2 C H 2 C=CHCH 2 CH 3 D H 3 CCH=CHCH 3 (Total for Question 8 = 1 mark) 9 Which of the following covalent bonds is the shortest? A H B H C H D H F Cl Br I (Total for Question 9 = 1 mark) *H34471A0528* 5 Turn over

6 10 Which of the following substances, obtained from the fractional distillation of crude oil, has the lowest boiling temperature? A B C D refinery gas kerosene diesel oil lubricating oil (Total for Question 10 = 1 mark) 11 Sodium hydrogensulfate, NaHSO 4, reacts with sodium hydroxide, NaOH, as shown below. NaHSO 4 (aq) + NaOH(aq) Na 2 SO 4 (aq) + H 2 O(l) mol of sodium hydrogensulfate is neutralized with dilute sodium hydroxide, concentration mol dm 3. Calculate the volume of sodium hydroxide required. A 20.0 cm 3 B 50.0 cm 3 C 100 cm 3 D 500 cm 3 (Total for Question 11 = 1 mark) 12 Which of the following ions would undergo the greatest deflection in a mass spectrometer? A 35 Cl 2+ B 35 Cl + C 37 Cl + D 35 Cl 37 Cl + (Total for Question 12 = 1 mark) 6 *H34471A0628*

7 13 Which pair of atomic numbers represents elements which are both in the p-block of the Periodic Table? A 4, 8 B 6, 12 C 8, 16 D 10, 20 (Total for Question 13 = 1 mark) 14 The electronic structure of an atom of an element in Group 6 of the Periodic Table could be A 1s 2 2s 2 2p 2 B 1s 2 2s 2 2p 4 C 1s 2 2s 2 2p 6 3s 2 3p 6 3d 6 4s 2 D 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 (Total for Question 14 = 1 mark) 15 Which of the following formulae for compounds of germanium, Ge, is unlikely to be correct, given the position of germanium in the Periodic Table? A GeF 3 B GeS 2 C GeO 2 D GeH 4 (Total for Question 15 = 1 mark) Use this space for any rough working. Anything you write in this space will gain no credit. *H34471A0728* 7 Turn over

8 16 The electronic configurations of the atoms of four different elements are given below. For which element would you expect the value of the first ionization energy to be the largest? A 1s 1 B 1s 2 C 1s 2 2s 1 D 1s 2 2s 2 (Total for Question 16 = 1 mark) 17 Which of the following gas samples occupies the greatest volume at the same temperature and pressure? [Relative atomic masses: H = 1; C = 12; O = 16; F = 19; Ne = 20] A B C D 1 gram of ethane 1 gram of oxygen 1 gram of fluorine 1 gram of neon (Total for Question 17 = 1 mark) 18 Which of the following has the smallest ionic radius? A F B Na + C Mg 2+ D O 2 (Total for Question 18 = 1 mark) Use this space for any rough working. Anything you write in this space will gain no credit. 8 *H34471A0828*

9 19 Which of the following does not have exactly 10 electrons? A An ion of fluorine, F B A molecule of methane, CH 4 C A molecule of nitrogen, N 2 D An ion of sodium, Na + (Total for Question 19 = 1 mark) 20 Which of the following statements correctly describes an environmental problem caused by the burning of hydrocarbon fuels? A The carbon dioxide is toxic and kills plants. B The smoke produced reflects sunlight and leads to global warming. C The water produced results in a damaging increase in rainfall. D The carbon dioxide produced absorbs heat radiated from the Earth and leads to global warming. (Total for Question 20 = 1 mark) TOTAL FOR SECTION A = 20 MARKS Use this space for any rough working. Anything you write in this space will gain no credit. *H34471A0928* 9 Turn over

10 SECTION B Answer ALL the questions. Write your answers in the spaces provided. 21 This question is about hydrocarbons. (a) Liquefied petroleum gas (LPG) is a fuel sold as an alternative to petrol. It is a mixture of liquefied C 3 and C 4 alkanes. (i) Suggest a reason why the alkanes are liquefied. (1) (ii) There are two C 4 alkanes. Draw skeletal formulae of each of the C 4 alkanes in the spaces provided. Name each alkane. (4) First skeletal formula Second skeletal formula Name:... Name:... (iii) Complete the following sentence. (1) Compounds with the same molecular formula but different structural formula are called *H34471A01028*

11 (b) Propane, C 3 H 8, reacts with chlorine, Cl 2, in a substitution reaction. C 3 H 8 + Cl 2 C 3 H 7 Cl + HCl The mechanism for this reaction is described in three stages. (i) Give the initiation step for this reaction and state the condition necessary for this step to occur. (2) Initiation step Condition... (ii) Give the TWO propagation steps for this reaction. (2) (iii) Give a possible termination step for this reaction. (1) *H34471A01128* 11 Turn over

12 (c) Myrcene, C 10 H 16, is a naturally occurring compound which is used in perfumes. H 3 C C CH CH 2 CH 2 C CH CH 2 CH 3 Myrcene CH 2 (i) Name the functional group in myrcene. (1) (ii) What colour change would you observe when bromine, dissolved in an organic solvent, is added to myrcene? (1) From... To... (iii) Classify the type and mechanism of the reaction that occurs when myrcene reacts with bromine, Br 2. (2) 12 *H34471A01228*

13 (iv) In an experiment, 1.36 g of myrcene (molar mass: 136 g mol 1 ) was found to react with 0.72 dm 3 of hydrogen, H 2, in the presence of a nickel catalyst. Use this information to draw the structural formula of the product of the reaction between myrcene and hydrogen. [Assume the molar volume of H 2 under the conditions of the experiment is 24 dm 3 mol 1.] (2) Calculation Hence structural formula of the product *H34471A01328* 13 Turn over

14 (d) Myrcene is one of a group of compounds related to 2-methylbut-2-ene shown below. CH 3 C H C CH 3 CH 3 2-methylbut-2-ene undergoes addition polymerization in a similar way to ethene. Draw the structural formula of the repeat unit of the polymer formed. (2) (Total for Question 21 = 19 marks) 14 *H34471A01428*

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16 22 The Born-Haber cycle for the formation of sodium chloride from sodium and chlorine may be represented by a series of steps labelled A to F as shown. Na + (g) + Cl(g) F A Na + (g) + Cl (g) Na + (g) + ½Cl 2 (g) B Na(g) + ½Cl 2 (g) E C Na(s) + ½Cl 2 (g) D NaCl(s) 16 *H34471A01628*

17 (a) (i) Complete the table below by adding the letters A to F next to the corresponding energy changes. (3) Energy change Letter ΔH /kj mol 1 Lattice energy for sodium chloride 775 Enthalpy change of atomization of sodium +109 Enthalpy change of atomization of chlorine +121 First ionization energy of sodium +494 First electron affinity of chlorine Enthalpy change of formation of sodium chloride 411 (ii) Calculate the first electron affinity of chlorine, in kj mol 1, from the data given. (2) *H34471A01728* 17 Turn over

18 (b) Lattice energies can be calculated from electrostatic theory (theoretical values) as well as by Born-Haber cycles (experimental values). Compound Experimental lattice energy Theoretical lattice energy / kj mol 1 / kj mol 1 NaCl Agl (i) Comment on the fact that there is close agreement between the values for sodium chloride, NaCl. (1) *(ii) Explain, in terms of chemical bonding, why the experimental value for silver iodide, AgI, is more exothermic than the value calculated theoretically for the same compound. (2) 18 *H34471A01828*

19 *(c) Suggest why the first ionization energies of the Group 1 elements decrease down the group. (2) (Total for Question 22 = 10 marks) *H34471A01928* 19 Turn over

20 ± ± ± ± ± ± ± ± 23 The graph shows the variation in melting temperatures of the elements across Period 3 (Na to Ar) of the Periodic Table ± 1400 ± ± 1000 ± Melting temperature / C 800 ± 600 ± ± 200 ± 0± ±200 ± 3 ±400 ± Na Mg Al Si P S Cl Ar Element (a) Complete the table below to show the type of structure and bonding for the elements shown. Element Structure Bonding sodium silicon sulfur (3) (b) Explain why silicon has a much higher melting temperature than sulfur. (2) 20 *H34471A02028*

21 *(c) Explain why the melting temperature increases from sodium to aluminium. (2) (d) Magnesium forms the basic oxide magnesium oxide, MgO. This oxide is almost insoluble in water. On gentle warming with dilute sulfuric acid, magnesium oxide reacts to form aqueous magnesium sulfate solution. *(i) Describe how you would use the above reaction to prepare a pure sample of magnesium sulfate. (5) (ii) Suggest what action should be taken if a pupil spilt a small quantity of dilute sulfuric acid on a laboratory bench. (1) *H34471A02128* 21 Turn over

22 (e) The data in the table below will be useful when answering this question. Soluble in water Insoluble in water MgSO 4 MgCO 3 SrCO 3 SrSO 4 Magnesium carbonate reacts with dilute sulfuric acid. MgCO 3 (s) + H 2 SO 4 (aq) MgSO 4 (aq) + CO 2 (g) + H 2 O(l) (i) Explain why the reaction between strontium carbonate and dilute sulfuric acid stops after a few seconds. (1) (ii) Strontium sulfate is produced when aqueous sodium sulfate is added to aqueous strontium chloride. Give the ionic equation for the reaction, including state symbols. (2) (Total for Question 23 = 16 marks) 22 *H34471A02228*

23 24 Propanone, C 3 H 6 O, undergoes complete combustion to form carbon dioxide and water. C 3 H 6 O(l) + 4O 2 (g) 3CO 2 (g) + 3H 2 O(l) (a) In an experiment to calculate the enthalpy change of combustion for propanone, 2.90 g of propanone was burned completely in oxygen. The heat energy from this combustion raised the temperature of 200 g of water from 20.2 C to 78.4 C. The specific heat capacity of water is 4.18 J g 1 C 1. (i) Calculate the number of moles of propanone present in 2.90 g. [The molar mass of propanone is 58 g mol 1.] (1) (ii) Use the expression energy transferred (J) = mass specific heat temperature capacity change to calculate the heat energy transferred to raise the temperature of 200 g of water from 20.2 C to 78.4 C. (2) (iii) Use your answers to (a)(i) and (ii) to calculate a value for the enthalpy change of combustion of propanone. Give your answer to three significant figures and include a sign and units. (3) *H34471A02328* 23 Turn over

24 (b) In another experiment, the enthalpy change of combustion for butanone, C 4 H 8 O, was found to be 1300 kj mol 1. A Data Book value for the standard enthalpy change of combustion for butanone is 2440 kj mol 1. (i) Suggest a reason why the value obtained in the experiment is so different from the Data Book value. (1) (ii) This Data Book value ( 2440 kj mol 1 ) refers to the following equation. C 4 H 8 O(l) + 1 ½O 2 (g) 4CO 2 (g) + 4H 2 O(l) How would the value be different if it referred to the formation of water in the gaseous state? Justify your answer. (2) Difference... Justification... (c) Standard enthalpy changes of combustion can be used to calculate the standard enthalpy change of formation of a compound. (i) Define the term standard enthalpy change of formation, making clear the meaning of standard in this context. (3) 24 *H34471A02428*

25 (ii) Use the standard enthalpy changes of combustion, ΔH c, given in the table below to find the standard enthalpy change of formation for ethanoic acid, CH 3 COOH, in kj mol 1. Substance ΔH c / kj mol 1 C(s, graphite) 394 H 2 (g) 286 CH 3 COOH(l) 870 2C(s, graphite) + 2H 2 (g) + O 2 (g) CH 3 COOH(l) (3) (Total for Question 24 = 15 marks) TOTAL FOR SECTION B = 60 MARKS TOTAL FOR PAPER = 80 MARKS *H34471A02528* 25

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